New York state is the easiest place for underage drinkers to illegally purchase booze, a new survey shows.

About one in six New Yorkers under the age of 21 reported they were able to buy their own liquor over the prior 30 days, according to the National Survey on Drug Use and Health report.

New York’s 15 percent average was well above the US average of 8.7 percent and about seven times the rate of the toughest states for teens to buy alcohol: New Mexico (2.5 percent), Idaho and Oregon (2.6). The survey covers the years 2008 through 2010.

Other lax states where youths can buy booze include Lousiana (14 percent), North Carolina (13), Connecticut (12.7) and Rhode Island and the District of Columbia (11).

“Despite the efforts to limit access, underage drinkers still are able to obtain alcohol, and many are able to purchase alcohol themselves,” the federal report said.

New York ranked seventh highest for the percentage of minors who drank alcohol in the prior month — 31.6 percent.

Vermont led the nation with 37 percent of youths imbibing, followed by New Hampshire (36), North Dakota (35), Colorado (33) and Connecticut and Massachusetts (32).

Utah — with a large Mormon population whose faith forbids alcohol consumption — had the fewest teen drinkers, 14.3 percent.

New York lawmakers and substance-abuse experts complained of weak enforcement of underage alcohol prohibitions, particularly in New York City, because it’s a low priority. They said there’s stricter enforcement against underage drinking in bars and clubs than for illegal alcohol sales in grocery or liquor stores.

“I don’t remember the last time a bodega or grocery got a fine for giving alcohol to a minor in my district,” said state Sen. Marty Golden (R-Brooklyn). “There’s a lack of will, a lack of enforcement.”

Part of the problem is that parents and society as a whole are more accepting of kids using booze rather than other drugs, said Luke Nasta, director of the Staten Island-based Camelot Counseling Centers.

“It’s a back-door acceptance,” Nasta said. “It’s not a priority. It’s a sign of surrender on the part of society.”

The New York State Health and Health Planning Council has proposed a crackdown on underage and adult binge drinking. But Gov. Cuomo shot down as anti-businesss the recommendations to curb boozing by increasing taxes on liquor, limiting the number of new bars and liquor stores, and restricting the hours of existing ones.